Method for the isolation of sulfuric acid mono-[3({1-[2-(4-fluorophenyly)-ethyl]-piperidin-4-yl}-2-methoxy-phenyl}ester

ABSTRACT

The present invention is directed to the method of isolation of sulfuric acid mono-[3-({1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-hydroxy-methyl)-2-methoxy-phenyl]ester, a metabolite of the 5HT 2A  antagonist (+)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol.

[0001] This application is a division of U.S. application Ser. No.10/200,821, filed Jul. 22, 2002, now allowed, which is a division ofSer. No. 09/615,246, filed Jul. 13, 2000, now U.S. Pat. No. 6,465,490B1, issued, Oct. 15, 2002, which claims the benefit of U.S. ProvisionalApplication No. 60/198,215, field Jul. 16, 1999.

FIELD OF THE INVENTION

[0002] The present invention relates to a method of isolation ofsulfuric acidmono-[3-({1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-hydroxy-methyl)-2-methoxy-phenyl]ester.It is a pharmaceutically active compound useful as an antagonist ofserotonin at the 5HT_(2A) receptor. It is useful in treating conditionsand diseases such as schizophrenia, anxiety, variant angina, anorexianervosa, Raynaud's phenomenon, intermittent claudication, coronary orperipheral vasospasms, fibromyalgia, cardiac arrhythmias, thromboticillness, controlling the extrapyramidal symptoms associated withneuroleptic therapy, depressive and bipolar disorders,obsessive-compulsive disorders, insomnia and sleep apnea.

BACKGROUND OF THE INVENTION

[0003](+)-α-(2,3-Dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanolhas the following structure:

[0004] It is a novel pharmaceutically active compound in the treatmentof conditions and diseases useful as an antagonist of serotonin at the5HT2A receptor, and as such, is useful in a variety of treatments suchas schizophrenia, anxiety, variant angina, anorexia nervosa, Raynaud'sphenomenon, intermittent claudication, coronary or peripheralvasospasms, fibromyalgia, cardiac arrhythmias, thrombotic illness,controlling the extrapyramidal symptoms associated with neuroleptictherapy, depression, bipolar disorders, obsessive-compulsive disorders,insomnia and sleep apnea.α-(2,3-Dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanolhas been generically described in U.S. Pat. No. 5,169,096, issued Dec.8, 1992, the disclosure of which is incorporated herein by reference.(+)-α-(2,3-Dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]4-piperidinemethanolwas thereafter described in U.S. Pat. No. 5,134,149, issued Jul. 28,1992, the disclosure of which is incorporated herein by reference. U.S.Pat. No. 5,700,813, issued Dec. 23, 1997, U.S. Pat. No. 5,700,812,issued Dec. 23, 1997, U.S. Pat. No. 5,561,144, issued Oct. 1, 1996, U.S.Pat. No. 5,721,249 issued February 23, 1998 and U.S. Pat. No. 5,874,445issued Feb. 23, 1999, the disclosure of each which is incorporatedherein by reference, describe the use of(+)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanolas 5HT_(2A) receptor antagonists in the treatment of a number of diseasestates as described above. Other U.S. patents, which describe the use ofthe generic species in the treatment of a number of disease states, areU.S. Pat. Nos. 4,783,471; 4,877,798; 4,908,369; 4,912,117; 5,021,428;5,106,855; 5,618,824 and U.S. Pat. No. 5,478,846, which genericallydiscloses intermediates. Each of the preceding disclosures isincorporated herein by reference.

[0005] The compound of the present invention has been found to be anactive metabolite of(+)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanolby virtue of its ability to act as an antagonist at the 5HT_(2A)receptor, and represents the major metabolite of(+)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanolfound in plasma. The unsulfated version of the present invention(+)-α-(3-hydroxy-2-methoxyphenyl)-1-(2-(4-fluorophenyl)ethyl)4-piperidinemethanolis also a metabolite of(+)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]4-piperidinemethanolas described in Heath, T. G. et al. J. Am. Soc. Mass Spectrom. (1997),8(4), 371-379, and Scott, D. et al. J. Pharm. Biomed. Anal. (1998),17(1), 17, incorporated herein by reference. Even though the presentinvention is a mono sulfated conjugate of(+)-α-(3-hydroxy-2-methoxyphenyl)-1-(2-(4-fluorophenyl)ethyl)-4-piperidinemethanol,unexpectedly, according to tests described hereafter, it has been foundto cross the blood-brain barrier and therefore may be useful in thetreatment of central nervous system conditions or diseases which aretreated by antagonizing the effects of serotonin at the 5HT_(2A)receptor.

[0006] It is an object of the present invention to provide a compounduseful in treating a variety of diseases or conditions. This compoundshould have a binding profile (affinity or lack of affinity for specificreceptors), which permits therapeutic activity without undue sideeffects. For example, too much affinity for the alpha1 receptor mayresult in orthostatic hypotension and sedation. Too much affinity forthe dopamine 2 (D₂) receptor can result in hyperprolactinemia,extrapyramidal side effects (EPS) and tardive dyskinesia. Also,preferably the present invention should cross the blood-brain barrier inorder to be active against diseases or conditions that affect thecentral nervous system. The present invention solves these problems byhaving an effective binding profile sufficient to treat certain diseasesor conditions without significant side effects and treats certaincentral nervous systems diseases or conditions.

SUMMARY OF THE PRESENT INVENTION

[0007] The present invention is a method of isolating a compound offormula I or its enantiomers from an appropriate sample comprising thesteps of:

[0008] a) collecting the sample from a patient wherein the patient hasbeen administered a therapeutically sufficient amount of(+)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol;

[0009] b) optionally preparing the sample for isolation of the compoundof Formula I or its enantiomers; and

[0010] c) isolating the compound of Formula I or at least one enantiomerfrom the sample.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0011] In general, various terms as used herein shall have the followingmeanings unless otherwise defined:

[0012] (1) “Pharmaceutically acceptable salt” means either an acidaddition salt or a basic addition salt, which is compatible withtreatment of patients for the intended use.

[0013] “Pharmaceutically acceptable acid addition salt” is a non-toxicorganic acid addition salt of the base compounds represented by FormulaI, II or III or any of its intermediates. Some examples of inorganicacids which form suitable salts include hydrochloric, hydrobromic,sulfuric and phosphoric acid and acid metal salts such as sodiummonohydrogen orthophosphate, and potassium hydrogen sulfate.Illustrative organic acids, which form suitable salts, include themono-, di, and tricarboxylic acids. Examples of such acids are acetic,glycolic, lactic, pyruvic, malonic, succinic, glutaric, fumaric, malic,tartaric, citric, ascorbic, maleic, hydroxymaleic, benzoic,hydroxybenzoic, phenylacetic, cinnamic, salicylic, 2-phenoxybenzoic, andsulfonic acids such as p-toluenesulfonic acid, methane sulfonic acid and2-hydroxyethane sulfonic acid. Such salts can exist in either a hydratedor substantially anhydrous form. In general, the acid additionhydrophilic organic salts in comparison to their free base formsgenerally demonstrate higher melting points.

[0014] “Pharmaceutically acceptable base addition salts” means non-toxicorganic or inorganic basic addition salts of the compounds of Formula(I) or any of its intermediates. Examples are alkali metal oralkaline-earth metal hydroxides such as sodium, potassium, calcium ororganic amines such as methylamine, trimethylamine and picoline.

[0015] (2) “Patient” means a warm blooded animal, such as, for example,rat, mouse, dog, cat, guinea pig, and primates such as a human.

[0016] (3) “Treat” or “treatment” means to prevent or alleviatesymptoms, eliminate the causation of the symptoms either on a temporarybasis, or to prevent or slow the appearance of symptoms of the nameddisorder or condition.

[0017] (4) “Therapeutically sufficient amount” means a quantity of thecompound that is effective in treating the named disorder or condition.

[0018] (5) “Amount sufficient to antagonize the effects of serotonin atthe 5 HT2A receptor” means a quantity of the compound that is effectivein antagonizing the effects of serotonin at the 5HT_(2A) receptor.

[0019] (6) “Administering or administration” means a suitable route forgiving a therapeutically sufficient amount of drug to a patient.Examples of suitable routes are oral, buccal, sublingual, parenteral,intravenous and topical, including a topical patch administration.Furthermore, this also means giving a prodrug to the patient in order toproduce the compound of interest at the site of action in the body. Forexample, the prodrug(+)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanolis administered to the patient to provide at least the compound sulfuricacid mono-(+)-[3-({1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-hydroxy-methyl)-2-methoxy-phenyl]ester and possibly the (−) enantiomerthereof.

[0020] (7) “Schizophrenia” means a condition where a patient suffers amental disturbance that lasts at least 6 months and includes 1 month ofactive-phase symptoms, such as two or more of the following: delusions,hallucinations, disorganized speech, grossly disorganized or catatonicbehavior, and negative symptoms.

[0021] (8) “Anxiety” means a condition where a patient suffers anapprehension of danger and dread accompanied by restlessness, tension,tachycardia and dyspnea unattached to a clearly identifiable stimulus.

[0022] (9) “Variant angina” means a condition where the patient suffersfrom coronary vasospasms, which produce the chest pains associated withangina. These vasospasms typically occur while the patient is at rest.

[0023] (10) “Anorexia nervosa” means a condition where a patient refusesto maintain a minimally normal body weight and is intensely afraid ofgaining weight, and exhibits a significant disturbance in the perceptionof the shape or size of his or her body.

[0024] (11) “Raynaud's phenomenon” means a condition where the patientsuffers from a spasm of the digital arteries, with blanching andnumbness of or pain of the fingers, often precipitated by cold.

[0025] (12) “Intermittent claudication” means a condition where thepatient suffers from, due to ischemia of the muscles, attacks oflameness and pain, brought on by walking, chiefly in the calf muscles;however, the condition may occur in other muscle groups.

[0026] (13) “Coronary or peripheral vasospasms” means a condition wherethe patient suffers from contraction and hypertonia of the muscularcoats of the cardiac or peripheral blood vessels.

[0027] (14) “Fibromyalgia” means a condition where the patient sufferschronically from numerous symptoms such as, for example, widespreadgeneralized musculoskeletal pains, aching, fatigue, morning stiffnessand a sleep disturbance which can be characterized as an inadequacy ofstage 4 sleep.

[0028] (15) “Cardiac arrhythmia” means a condition where the patientsuffers from any variation from the normal rhythm of the heart beat.

[0029] (16) “Thrombotic illness” means a condition where the patientsuffers from a clotting within a blood vessel, which may causeinfarction of tissues supplied by the vessel.

[0030] (17) “Extrapyramidal symptoms” means a condition where thepatient suffers from side effects from the administration of neurolepticagents such as haloperidol and chloropromazine. These extrapyramidalside effects (EPS) can encompass Parkinsonian-like syndromes, akathasiaand acute dystonic reactions.

[0031] (18) “Depression” means a condition where the patient suffersfrom a temporary mental state or chronic mental disorder characterizedby feelings of sadness, loneliness, despair, low self-esteem andself-reproach; accompanying signs include psychomotor retardation orless frequently agitation, withdrawal from social contact and vegetativestates such as loss of appetite and insomnia.

[0032] (19) “Bipolar disorder” means a condition where the patientsuffers from alternating periods of euphoria and depression.

[0033] (20) “Obsessive-compulsive disorders” or “OCD” means a conditionwhere the patient exhibits recurrent obsessions or compulsions that aresevere enough to be time consuming (i.e., take more than an hour a day)or cause marked distress or significant impairment. Obsessions arepersistent ideas, thoughts, impulses, or images that are experienced asintrusive and inappropriate and that cause marked anxiety or distress.Compulsions are repetitive behaviors (e.g., hand washing, ordering,checking) or mental acts (e.g., praying, counting, repeating wordssilently) the goal of which is to prevent or reduce anxiety or distress,not to provide pleasure or gratification.

[0034] (21) “Insomnia” means a condition where the patient suffers froman inability to sleep in the absence of external impediments, during theperiod when sleep should normally occur.

[0035] (22) “Sleep apnea” means a condition where the patient suffersfrom a stoppage of breathing for at least 10 seconds or more, andusually greater than 20 times/hour, causing measurable blooddeoxygenation.

[0036] (23) “Pharmaceutically acceptable carrier” is a non-toxicsolvent, dispersant, excipient, adjuvant or other material, which ismixed with the active ingredient in order to permit the formation of apharmaceutical composition, i.e., a dosage form capable ofadministration to the patient. One example of such a carrier ispharmaceutically acceptable oil typically used for parenteraladministration.

[0037] (24) “Enantiomers” are a pair of isomers that are mirror imagesof each other and not superposable.

[0038] (25) “Racemate” means a composite of two enantiomeric species. Itis devoid of optical activity.

[0039] (26) “Stereoisomer” is a general term for all isomers ofindividual molecules that differ only in the orientation of their atomsin space. It includes mirror image isomers (enantiomers), geometric(cis/trans) isomers and isomers of compounds with more than one chiralcenter that are not mirror images of one another (diastereomers).

[0040] (27) “C₁-C₄ alkyl” and C₁₋₆ alkyl” means a straight or branchedchain hydrocarbon radical of one to four and one to six carbon atoms.Included within the scope of these terms are methyl, ethyl, n-propyl,isopropyl, n- butyl, isobutyl, pentyl, neopentyl, hexyl and the like.

[0041] (28) “Aralkyl” means an aryl or diaryl moiety connected to theremainder of the molecule via an alkylene bridge. This alkylene bridgecan be straight or branched-chained and is one, two, three, four, fiveor six carbons in length. “Aryl means an aromatic radical having sixatoms in a single ring system such as phenyl or a fused ring system suchas 1-napthyl, 2-napthyl and the like. The aryl or diaryl group may beoptionally substituted as described herein. The substitutions may be atthe ortho, meta or para positions as appropriate. Examples of preferredaralkyls are benzyl, phenylethyl, propylphenyl and diphenylbutyl.

[0042] (29) “Optionally substituted” means that the referenced moiety issubstituted as defined herein by the same or different substituents,i.e. independently selected, from the group; of hydrogen, halogen(fluorine, chlorine, iodine or bromine), C₁₋₆ alkyl, C₁₋₆ alkoxy,C(═O)H, C(═O)C₁₋₆ alkyl, CF₃ or hydroxy with one, two or threesubstituents as is suitable to the structure.

[0043] (30) “Prodrug” means a compound given to a patient, which is thenmetabolized in the patient to another active compound. In the presentinvention the prodrug is(+)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol.

[0044] (31) “Sample” means a quantity of either plasma, urine or othercomponent of the body from which the compounds of the present inventionmay be found and isolated therefrom.

[0045] (32) “Optically active isomers” are isomers that rotate the planeof polarized light and are designated (+) or (−).

[0046] The compounds of the invention may be prepared by the syntheticroutes described below in the Schemes or other methods, which may beapparent to those skilled in the art. The enantiomerically purecompounds of the invention may be prepared as outlined in Scheme A. Thescheme illustrates the synthesis of the (+) enantiomer; however, aswould be evident to one with ordinary skill in the art, by starting withthe appropriate (−) enantiomer the sequence shown in Scheme A wouldafford the corresponding (−) enantiomer of the invention.

[0047] Step A1: The compound 1,(+)-α-(3-hydroxy-2-methoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol,a known metabolite of(+)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanolas described in Heath, T. G. et al. J. Am. Soc. Mass Spectrom. (1997),8(4), 371-379, and Scott, D. et al. J. Pharm. Biomed. Anal. (1998),17(1), 17-25, (also see Scheme C), is reacted with a suitable acylatingagent to provide the diprotected compound 2, wherein Pg is a protectinggroup such as C₁₋₆ alkylsulfonyl, trifluoroacetyl, or C(═O) C₁₋₆ alkylother protecting groups may be used as is known to one skilled in theart. The groups may be the same or different groups, but typically arethe same. Suitable acylating agents are, for example, anhydrides andacid chlorides or bromides, with anhydrides preferred. The reaction isperformed under standard acylating conditions well known to those withordinary skill in the art.

[0048] Step A2: The diprotected compound 2 is then selectivelyhydrolyzed to the monoprotected phenol 3. The reaction may be carriedout in an aqueous protic solvent with an alkali bicarbonate. Examples ofaqueous protic solvents are ethanol, methanol, propanol and isopropanolthat have been diluted with varying proportions of water. The preferredaqueous protic solvent is aqueous methanol. Examples of alkalibicarbonates are sodium, cesium or potassium bicarbonate, sodiumbicarbonate being preferred. The reaction temperature may vary from 0°C. to the boiling point of the solvent. The preferred temperature isbetween 0° C. and room temperature.

[0049] Step A3: The monoprotected phenol 3 is converted to theintermediate mono sulfuric acid ester 4 by reacting said monoprotectedphenol with a suitable sulfating agent. Suitable sulfating agents arethose compounds capable of adding sulfate at the desired position.Examples of suitable sulfating agents are sulfur trioxide pyridinecomplex, sulfur trioxide triethylamine complex, sulfur trioxidedimethylformamide complex, sulfuric acid-dicyclohexylcarbodiimide,chlorosulfonic acid with acid or base, pyridine sulfur trioxide complexbeing preferred. The reaction is carried out in an appropriate organicsolvent. Examples of appropriate organic solvents are benzene, toluene,acetonitrile, dimethylformamide, dichloromethane and chloroform. Thepreferred solvent is acetonitrile. The reaction temperature may varyfrom room temperature to the boiling point of the solvent, a temperatureof about 45° C. is preferred.

[0050] Step A4: Preferably without isolation of the sulfuric acid ester4 is reacted in situ with an alkali metal carbonate such as sodium,potassium, or cesium carbonate, potassium carbonate preferred, in anaqueous protic solvent such as methanol-water to afford the sulfuricacid ester alcohol 5. The reaction temperature may vary from roomtemperature to boiling point of the solvent, the boiling point of thesolvent is preferred.

[0051] Scheme B illustrates the synthesis of the racemate of 15 alsoknown as Formula I.

[0052] Step B1: Guiacol, the compound 6, available from the AldrichChemical Company, is reacted with a reagent to provide a suitableprotecting group, preferably a suitable trialkylsilyl halide to form themonomethoxysilylether derivative 7. Suitable trialkylsilyl halides, arecompounds that would react with a phenolic oxygen to produce a compoundwherein R₁═Si(R₄)₃ and R₄ is C₁₋₆ alkyl for example,t-butyldimethylsilyl chloride and triisopropylsilyl chloride, withtriisopropylsilyl chloride being preferred. The purpose of the silylsubstituent (R₁), besides protecting the phenolic oxygen, is also toinhibit abstraction of the aromatic hydrogen that is adjacent (ortho) tothe OR, substituent, when the compound is treated with a strong base.Consequently, upon reaction of said compound with a strong base, thearomatic hydrogen ortho to the methoxy substituent is abstractedregioselectively. Such a strategy has been previously invoked by B.Trost, et al., Tetrahedron Lett., 1985, 26, 123-126 and J. J. Landi, etal. Synthetic Commun., 1991, 21, 167-171 incorporated herein byreference. The reaction is typically effected by reaction of atrialkylsilyl halide, in the presence of a suitable nucleophiliccatalyst such as imidazole or 4-dimethylaminopyridine, imidazole beingpreferred, in a suitable polar aprotic solvent. Examples of polaraprotic solvents are dimethylformamide, 1-methyl-2-pyrrolidinone,dimethylsulfoxide, hexamethylphosphoramide, acetone and acetonitrile.The preferred solvent is dimethylformamide. The reaction can be run at atemperature from 0° C. to ambient temperature, ambient temperature beingpreferred.

[0053] Step B2: The silyl derivative 7 is then reacted with a C₁₋₄ alkyllithium, such as n-butyl, sec-butyl or t-butyl lithium, n-butyl lithiumbeing preferred, in an ethereal solvent, such as diethyl ether,tetrahydrofuran or dimethoxyethane, with tetrahydrofuran being thepreferred solvent. This results in the regioselective formation of theanion. Addition of a suitable N-protected piperidinyl Weinreb amidederivative 8, produces the ketone 9. Suitable N-protecting groups (R₂)are those that would be stable under the reaction conditions, andexamples can be found in Protective Groups in Organic Synthesis, 2ndedition, Theodora Greene, et al., John Wiley and Sons, Inc.,incorporated herein by reference. The reaction temperature may be variedbetween −78° C. to the boiling point of the solvent.

[0054] Step B3: The ketone 9 is N-deprotected to produce the aroylpiperidine 10. Reagents and conditions to effect the deprotection woulddepend upon the nature of the N-substituent and would be apparent to onewith ordinary skill in the art.

[0055] Step B4: Reaction of aroyl piperidine 10 with a suitablealkylating agent 11 forms the alkylated piperidine 12. A suitablealkylating agent is where X=a suitable leaving group. A “suitableleaving group” is a moiety that is displaced or removed for the reactionto take place. Examples of suitable leaving groups are halogens,benzenesulfonate, methanesulfonate or p-toluenesulfonate, withmethanesulfonate being preferred. The reaction is performed in thepresence of a suitable organic base, in a polar aprotic solvent.Examples of suitable organic bases are pyridine, triethylamine, lutidineand N-ethyldiisopropylamine, with N-ethyldiisopropylamine preferred.Examples of suitable polar aprotic solvents are acetone, acetonitrile,dimethylformamide, 1-methyl-2-pyrrolidinone, dimethylsulfoxide andhexamethylphosphoramide. The preferred solvent is acetonitrile. Thereaction may be conducted at room temperature to the boiling point ofthe solvent. The preferred temperature being the boiling point of thesolvent.

[0056] Step B5: The alkylated piperidine 12 is converted to the hydroxyketone 13 by treatment with a suitable desilylating agent in an etherealsolvent. A suitable desilylating agent is a compound, which removes thesilyl protecting group. Examples of suitable desilylating agents areammonium tetrafluoride, tetra-N-butylammonium fluoride and pyridinehydrofluoride, tetra-N-butylammonium fluoride being preferred. Suitableethereal solvents are diethyl ether, tetrahydrofuran or dimethoxyethane,tetrahydrofuran being preferred. The reaction temperature may vary from0C to the boiling point of the solvent, with ambient temperature beingpreferred.

[0057] Step B6: Hydroxy ketone 13 is converted to the intermediatesulfuric acid ester 14 by reacting said hydroxyketone with a suitablesulfating agent. Suitable sulfating agents are those compounds capableof adding sulfate at the desired position. Examples are sulfur trioxidepyridine complex, sulfur trioxide triethylamine complex, sulfur trioxidedimethylformamide complex, sulfuric acid-dicyclohexylcarbodiimide andchlorosulfonic acid with acid or base. The reagent sulfur trioxidepyridine complex being preferred. The reaction is carried out in anappropriate organic solvent for the reaction to occur. Examples ofappropriate organic solvents are benzene, toluene, acetonitrile,dimethylformamide, dichloromethane and chloroform. The preferred solventis acetonitrile. The reaction temperature may vary from room temperatureto boiling point of the solvent. The preferred temperature being theboiling point of the solvent.

[0058] Step B7: Preferably without isolation, the sulfuric acid esterketone 14 is reduced to the racemic alcohol ester 15, by an suitablereducing agent. A suitable reducing agent is a compound, which reducesthis ketone to the desired alcohol. Examples of suitable reducing agentsare alkali metal borohydrides, such as lithium or sodium borohydridewith sodium borohydride being the preferred reducing agent. The reactionis performed in an appropriate protic organic solvent such as ethanol,isopropanol, propanol or methanol, ethanol being the preferred solvent.The reaction temperature may vary from 0° C. to the boiling point of thesolvent, with room temperature being preferred.

[0059] Step B8: Optionally reacting compound 15 or its enantiomers withan inorganic or organic acid capable of forming a pharmaceuticallyacceptable salt.

[0060] In another embodiment of this invention, the method of synthesisof the intermediate alcohol 1 is described in Scheme C.

[0061] Step C1: The benzoyl piperidine 10 from Scheme B is reacted withthe acid halide 16 to obtain the ketoamide 17. The substituent Xrepresents a halogen chosen from Br, Cl and F with Cl being thepreferred halogen. The substituent R₁ represents the group Si(R₃)₄ andR₃ represents C₁₋₄ alkyl. The reaction can be performed under conditionsthat are well known to one skilled in the art, for instance, in asuitable organic solvent and in the presence of a suitable base.Examples of suitable organic solvents are aromatic hydrocarbons such asbenzene, toluene, mesitylene and xylenes; aliphatic hydrocarbons such aspentane, hexane and heptane and aliphatic ethers such as diethyl anddiisopropyl ether. The preferred solvent being toluene. Suitable baseswould be tertiary organic amines, and aqueous solutions of inorganicbases. Inorganic bases suitable for use in the present invention includealkali hydroxides, alkali carbonates and alkali bicarbonates. Mostpreferred is an aqueous solution of an alkali hydroxide such as sodiumhydroxide.

[0062] Step C2: The ketoamide 17 is reduced to produce the piperidinealcohol 18 as a racemate with a suitable reducing agent in an organicsolvent. Reducing agents suitable for use in the method are boranecomplexes, aluminum hydrides, alkali aluminum hydrides, alkaliborohydrides particularly in the presence of Lewis or organic acids. Thepreferred reducing agent is borane-methyl sulfide complex. Organicsolvents that can typically be used for the reaction are ether,tetrahydrofuran, dimethoxyethane and toluene, with toluene beingpreferred. The reaction temperature at which the reaction can be run mayvary from −50° C. to the boiling point of the solvent. Most preferred isa temperature of about −30° C. to room temperature.

[0063] In a further embodiment, the piperidine alcohol 18 can beobtained in an enantioenriched state by the addition of a catalyticamount of a chiral oxazaborolidine to Step C2 above. The use of suchreagents for the enantioselective reduction of ketones has beenillustrated in a review by Walbine S. et al., Tetrahedron Asymmetry,1992, 3, 1475-1504, incorporated herein by reference. Suitable chiraloxazaborolidines for the reaction are (R) or(S)-3,3-diphenyl-1-substituted pyrrolidino[1,2-c]-1,3,2-oxazaboroles and(R) or (S) -3,3-di-β-naphthyl-1-substitutedpyrrolidino[1,2-c]-1,3,2-oxazaboroles. The preferred chiral catalystbeing (R) or(S)-3,3-diphenyl-1-methylpyrrolidino[1,2-c]-1,3,2-oxazaborole(2-methyl-CBS-oxazaborolidine or methyl oxazaborolidine).

[0064] Step C3: Optionally, the piperidine alcohol 18 can be deprotectedto produce the racemate of the phenol alcohol 1 by treatment with asuitable desilylating agent in an organic solvent. A suitabledesilylating agent is a compound, which removes the silyl protectinggroup. Examples of suitable desilylating agents are ammoniumtetrafluoride, tetra-N-butylammonium fluoride and pyridinehydrofluoride, with ammonium tetrafluoride preferred. Suitable organicsolvents for the reaction are protic solvents such as alcohols orethereal solvents such as dialkylethers. The reaction temperature mayvary from ambient temperature to the boiling point of the solvent.

[0065] Step C4: The piperidine alcohol 18 as a racemate or inenantioenriched form can then be reacted with a suitable chiral acid togive a mixture of diastereomeric esters 19, wherein R₃ is a suitableresolving agent. Suitable resolving agent means a moiety capable ofseparating enantiomers from a racemate by formation of diastereomericesters. Some examples of suitable resolving agents are (R) or (S)mandelic acid, acetyl mandelic acid, α-methoxyphenylacetic acid,α-methoxy-α-(trifluoromethyl)-phenylacetic acid,-2-(6-methoxy-2-naphthyl)-propionic acid, ω-camphanic acid,trans-1,2-cyclohexane dicarboxylic acid anhydride and5-oxo-2-tetrahydrofurancarboxylic acid as described in Stereochemistryof Organic Compounds, Ernest L. Eliel et al., John Wiley & Sons, Inc.,incorporated herein by reference. The preferred resolving agent is (R)or (S) α-methoxyphenylacetic acid. The reaction is typically performedin an organic solvent in the presence of a coupling promoter such asdicyclohexylcarbodiimide or carbonyl diimidazole and a nucleophiliccatalyst such as imidazole or 4-dimethylamino-pyridine. The preferredcoupling promoter is dicyclohexylcarbodiimide, and the preferrednucleophilic catalyst is 4-dimethylaminopyridine. Suitable organicsolvents for the reaction are aprotic solvents such as chloroform,methylene chloride, dimethylformamide, acetonitrile and toluene, withmethylene chloride being preferred. The reaction may be performed atroom temperature to the boiling point of the solvent, the boiling pointof the solvent is the preferred temperature. The mixture ofdiastereomeric esters is then separated by techniques that are wellknown to one with ordinary skill in the art, to produce the twoindividual diastereomers of compound 19. Separation of thediastereomers, for example, can be accomplished by crystallization orcolumn chromatography, with the preferred method of separation beingchromatography.

[0066] Step C5: The pure individual diastereomer of 19 is converted tothe phenol ester 20 by treatment with a suitable desilylating agent in aprotic solvent. Examples of suitable desilylating agents are ammoniumtetrafluoride tetra-N-butylammonium fluoride and pyridine hydrofluoride,with ammonium tetrafluoride preferred. Suitable protic solvents aremethanol, ethanol, propanol, butanol and isopropanol, methanol beingpreferred. The reaction temperature may vary from ambient temperature tothe boiling point of the solvent, the boiling point of the solvent beingpreferred.

[0067] Step C6: The phenol ester 20 is hydrolyzed to a single enantiomerof the phenol alcohol 1 by reaction of the ester with a suitable base ina water-protic solvent solution. Suitable bases to effect the reactionare alkali metal hydroxides and carbonates, such as sodium, potassium,lithium and cesium hydroxides and carbonates, with the preferred basefor the reaction being potassium carbonate. Suitable water-proticsolvent solutions are methanol-water, ethanol-water, propanol-water,isopropanol-water and butanol-water, with methanol-water preferred. Thereaction temperature may vary from 0° C. to the boiling point of thesolvent, with a temperature of about 20-25° C. preferred.

[0068] Also, as a further embodiment of the invention compound 1 can beisolated as an acid addition salt, whose preparation can be accomplishedby methods that are well known to one with ordinary skill in the art.

[0069] The compounds of the current invention may be isolated from asample such as human plasma by taking a sample of said human plasma froma patient that has been administered a therapeutically effective amountof(+)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol,treating the sample by methods well-known to one with ordinary skill inthe art, and subjecting said sample to isolation techniques such aschromatography. Chromatography of the sample can be accomplished, forexample, by such techniques as high performance liquid chromatography,column chromatography, thin layer chromatography and gas chromatography.The most preferred method of isolation is high performance liquidchromatography.

[0070] The stereochemistry of the isolated compound will be dependentupon the metabolic process, and thus may be isolated from the patient asa racemate or a single enantiomer.

[0071] The dosage range at which sulfuric acid mono-[3-({1-[2-(4-fluoro-phenyl) ethyl]-piperidin-4-yl}-hydroxy-methyl)-2-methoxy-phenyl]ester and its enantiomers exhibittheir ability to block the effects of serotonin at the 5HT_(2A) receptorcan vary depending upon the particular disease or condition beingtreated and its severity, the patient, other underlying disease statesthe patient is suffering from, and other medications that may beconcurrently administered to the patient. Generally though, thecompounds will exhibit their serotonin 5HT_(2A) antagonist properties ata dosage range of from about 0.001 mg/kg of patient body weight/day toabout 100.0 mg/kg of patient body weight/day. These compounds aretypically administered from 1-4 times daily. Alternatively, they can beadministered by continuous infusion. The compounds can be administeredorally or parenterally to achieve these effects.

[0072] The compound of the present invention intended for administrationcan be formulated into pharmaceutical dosage forms using techniques wellknown in the art. For oral administration, the compound can beformulated into solid or liquid preparations such as capsules, pills,tablets, lozenges, melts, powders, suspensions, or emulsions. Solid unitdosage forms can be capsules of the ordinary gelatin type containing,for example, surfactants, lubricants and inert fillers such as lactose,sucrose, and cornstarch or they can be sustained release preparations.In another embodiment, the compound can be tableted with conventionaltablet bases such as lactose, sucrose, and cornstarch in combinationwith binders, such as acacia, cornstarch, or gelatin, disintegratingagents such as potato starch or algenic acid, and a lubricant such asstearic acid or magnesium stearate. Liquid preparations are prepared bydissolving the active ingredient in an aqueous or non-aqueouspharmaceutically acceptable solvent, which may also contain suspendingagents, sweetening agents, flavoring agents, and preservative agents asare known in the art.

[0073] For parenteral administration, the compound or its salts may bedissolved in a physiologically acceptable pharmaceutical carrier andadministered as either a solution or a suspension. Illustrative ofsuitable pharmaceutical carriers are water, saline, dextrose solutions,fructose solutions, ethanol, or oils of animal, vegetative, or syntheticorigin. The pharmaceutical carrier may also contain preservatives,buffers, etc. as are known in the art.

[0074] The compound may be admixed with any inert carrier and utilizedin laboratory assays in order to determine the concentration of thecompounds within the urine, serum, etc. of the patient as is known inthe art.

[0075] The following examples present typical syntheses as described bySchemes A, B and C and methods for isolation and biological assays.These examples are understood to be illustrative only and are notintended to limit the scope of the invention in any way. As used in thefollowing examples, the following terms have the meanings indicated: “g”refers to grams, “mg” refers to milligrams “mmol” refers to millimoles,mol refers to moles, “mL” refers to milliliters, “μL” refers tomicroliters “μm” refers to micromoles, “μM” refers to micromolar, “mM”refers to millimolar “ppm” refers to parts per million, “C” refers toCelsius, “THF” refers to tetrahydrofuran, “MeOH” refers to methanol,“EtOAc” refers to ethyl acetate, “TLC” refers to thin layerchromatography, “LC” or “HPLC” refers to high performance liquidchromatography and “CIMS” refers to chemical ionization mass spectrum,“CIDMS” refers to collision-induced dissociation mass spectrum, “NMR”refers to nuclear magnetic resonance, “IR” refers to infraredspectroscopy “t_(R)” means retention time, “R_(f)” means the ratio ofthe distances which the sample migrates (on TLC) as compared to thedistance from the starting point of the solvent front.

EXAMPLE 1A

[0076]

2-(4-Fluoro-phenyl)-1-[4-(2-methoxy-3-triisopropylsilanyloxy-benzoyl)-piperidin-1-yl]-ethanone

[0077] To a solution of4-(2-methoxy-3-triisopropylsilanyloxy-benzoyl)-piperidine of Example 2Cbelow (287 g, 0.72 mol) in toluene (750 mL) add 50% NaOH (102 mL) andH₂O (300 mL). Cool the mixture in an ice bath and add 4-fluorophenacetylchloride (221.3 g, 1.28 mol) dissolved in toluene over a period of 30min. Allow the reaction to warm to room temperature, and stir for 2 h.Add H₂O (500 mL), stir for 0.5 h and separate the phases. Dry theorganic layer (MgSO₄) and concentrate to obtain 482 g of a brown oil.Purify the oil by flash chromatography over silica gel in three separateportions, eluting with ethyl acetate/hexanes. Combine like fractions toobtain two batches of oil: 123 g and 269 g. Treat the smaller batch with1:9 ethyl acetate/hexane and filter away 28 g of 4-flurorophenyl aceticacid. Concentrate the filtrate to obtain 95 g of oil, combine with thelarger batch and dissolve in 1:1 ethyl acetate/hexane (1.5 L). Wash theorganic solution with 4% NaOH (1 L), 2% NaOH (1 L), 2% HCl (1 L),saturated NaHCO₃ (1 L) and H₂O (1 L). Dry the organic layer (MgSO₄),filter and concentrate to obtain 270 g of the title compound.

EXAMPLE 1B

[0078]

{1-[2-(4-Fluoro-phenyl)-ethyl]-piperidin-4-yl}-(2-methoxy-3-triisopropylsilanyloxy-phenyl)-methanol

[0079] To a solution of2-(4-Fluoro-phenyl)-1-[4-(2-methoxy-3-triisopropylsilanyloxy-benzoyl)-piperidin-1-yl]-ethanone,Example 1A (262 g, 0.496 mol) in toluene (3.8 L) at −38° C. add(R)-methyloxoazaborolidine (150 mL, 0.15 mol, of 1M solution intoluene), follow with the addition of borane dimethylsulfide complex(750 mL of a 2M solution in toluene, 1.5 mol), over a 2 h period at −30°C. Stir between −25° C. to −28° C. overnight and then allow the reactionto warm to ambient temperature over a 2 h period. Slowly add MeOH (500mL) over a1 h period and then concentrate the solution to obtain 363 gof yellow oil. Add MeOH (1.8 L) to the oil and concentrate under reducedpressure at 80° C. to obtain 341 g of a yellow oil. Purify the oil byplug filtration through silica gel eluting with 1:1 MeOH/CHCl₃. Combineand concentrate the desired fractions to obtain 250 g of product.Further purify the product by column chromatography over silica geleluting with 1:3 EtOAc/hexane (20 L), 1:1 EtOAc/hexane (20 L) and 1:1CHCl₃/MeOH (40 L). Collect and concentrate like fractions to obtain 214g of oil. Dissolve the oil in CHCl₃ (500 mL)/toluene (600 mL), dry(MgSO₄) and concentrate to obtain 207 g of the title compound as a foam.

EXAMPLE 1C

[0080]

(S)-Methoxy-2-phenyl-acetic acid{1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-(2-methoxy-3-triisopropylsilanyloxy-phenyl)-methyl ester

[0081] Stir a solution of {1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-(2-methoxy-3-triisopropylsilanyloxy-phenyl)-methanol,Example 1B (233.5 g, 0.53 mol) in CHCl₃ (2 L), add(S)-(+)-α-methoxyphenyl acetic acid (91 g, 0.55 mol) in CH₂Cl₂ (40 mL)1,3-dicyclohexylcarbodiimide (11.2 g, 0.54 mol) and4-dimethylaminopyridine (0.3 g, 0.008 mol). Heat the reaction to refluxfor 17 h, cool in an ice bath and add hexane (1 L). Filter the mixtureto remove the by-product urea and concentrate to obtain 368 g of yellowoil. Add hexane (1.4 L) to the oil and heat to dissolve. Cool thesolution to ambient temperature and allow standing for 24 h. Filter offmore urea and concentrate the filtrate with 630 g of silica gel. Applythe coated silica gel to a column previously packed with silica gel andelute with 1:5 EtOAc/hexane (80 L) and 1:2 EtOAc/hexane (20 L).Concentrate like fractions and obtain a semi-solid. Treat the semi-solidwith hexane and filter away the last traces of the urea. Concentrate thefiltrate to obtain 207.2 g of yellow oil.

EXAMPLE 1D

[0082]

(S)-Methoxy-2-phenyl-acetic acid{1-[2-(4-fluoro-phenyl)-ethyl]-piperidin4-yl}-(3-hydroxy-2-methoxy-phenyl)-methyl ester

[0083] Add to methoxy-phenyl-acetic acid{1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-(2-methoxy-3-triisopropylsilanyloxy-phenyl)-methylester, Example 1C (207 g, 0.3111 mol) a 0.5M solution of methanolicammonium tetrafluoride (1.2 L, 0.6 mol) and reflux for 17.5 h.Concentrate and obtain 198 g of the title compound.

EXAMPLE 1E

[0084]

(+)-1-[2-(4-Fluorophenyl-)ethyl]-α-(3-hydroxy-2-methoxyphenyl)-piperidinemethanol

[0085] Add to a solution of methoxy-phenyl-acetic acid{1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-(3-hydroxy-2-methoxy-phenyl)-methylester, Example 1D (158.2 g, 0.311 mol) in MeOH (1.2 L), K₂CO₃ (96.2 g,0.676 mol). Stir the reaction mixture at ambient temperature for 16 hadd H₂O (163 mL) and continue to stir for 16.5 h. Cool the reaction toambient temperature and concentrate. Stir the residue in CHCl₃ (1.5L)-H₂O (1 L) for 10 min and separate the organic layer. Wash the organicphase with H₂O (500 mL), dry (MgSO₄) and concentrate to 140 g of whitefoam. Purify the product by flash chromatography over silica gel elutingwith 1.5:1 CHCl₃/MeOH (40 L) and CHCl₃/MeOH (20 L). Combine andconcentrate like fractions and dissolve the residue in EtOAc (1 L). Drythe solution (MgSO₄) and concentrate to obtain 86 g of the product as awhite foam. [α]_(D) (c=1.0, in methanol)=+25.30.

EXAMPLE 1F

[0086]

Aceticacid-(3-acetoxy-2-methoxy-phenyl)-{1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-methyl ester

[0087] Add acetic anhydride (5 mL), dropwise, over 10 min to a stirring,cooled (ice/water bath) solution of(+)-1-[2-(4-fluorophenyl-)ethyl]-α-(3-hydroxy-2-methoxyphenyl)-piperidinemethanol,Example 1E (4.0 g, 11.1 mmol) in pyridine (40 mL). Stir the reactionmixture overnight, while allowing the temperature to rise to ambienttemperature. Add dichloromethane (100 mL) and wash the organics twicewith aqueous bicarbonate solution (100 mL). Dry the organic layer overNa₂SO₄, filter and evaporate under vacuum and obtain 5.2 g of product.

EXAMPLE 1G

[0088]

Aceticacid-{1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-(3-hydroxy-2-methoxy-phenyl)-methylester

[0089] Stir overnight a mixture of the acetic acid-(3-acetoxy-2-methoxy-phenyl)-{1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-methyl ester, Example 1F(5.2 g, 1.1 mmol), NaHCO₃ (11 g, 130 mmol), methanol (100 mL) and water(50 μL). Add water (100 mL) and dichloromethane (100 mL), and separatethe layers. Extract the aqueous layer with dichloromethane (100 mL), andcombine the organic layers. Dry over Na₂SO₄ and filter. Remove thesolvent under vacuum and obtain 5.1 g of product.

EXAMPLE 1H

[0090]

Sulfuric acid mono-(+)-[3-(-{1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-hydroxy-methyl)-2-methoxy-phenyl]ester

[0091] Add sulfur trioxide pyridine complex (10 g, 62 mmol) to asolution of the aceticacid-{1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-(3-hydroxy-2-methoxy-phenyl)-methylester, Example 1G (5.1 g, 11.1 mmol) in acetonitrile (50 mL), and heatat 45° C. for 18 h. Cool the mixture to ambient temperature and addwater (70 mL), methanol (70 mL) and K₂CO₃ (26 g, 0.194 mol). Reflux themixture for 12 h. Evaporate the acetonitrile and methanol and acidifythe remaining aqueous portion to pH=6. Collect the resultingprecipitate, rinse with water and dry to obtain 3.0 g of a light, brownsolid. The solid is 98% pure by LC (Zorbax Rx C8, 5μ, 250×4.6 mm, 0.17Macetic acid-0.05M ammonium acetate buffer/acetonitrile, 75:25. Flow: 0.8mL/min) t_(R)=9.40 min. CIMS, m/z=342 (M+H—SO₃—H₂O)⁺. ¹H NMR (300 MHz,DMSO-d₆) δ (ppm) 7.40 (d, 1H), 7.35 (t, 2H), 7.12 (t, 2H), 7.00 (d, 1H),6.95 (d, 2H), 4.95 (s, 1H), 4.63 (t, 1H), 3.79 (s, 3H), 3.50-2.40(series of broad peaks, 9H), 1.90-1.40 (series of broad peaks, 5H). ¹³CNMR (75 MHz, DMSO-d₆) δ=162.25, 159.95, 147.75, 145.59, 137.02, 130.05,122.20, 121.5, 119.95, 115.05, 115.00, 69.03, 60.09, 57.00, 52.00,33.33, 29.02, 26.02, 25.00, 24.05. ¹⁹F NMR (376 MHz, DMSO-d₆) δ=−117.00.[α]_(D) (22° C., c=0.6033 in 2:1 DMSO/MeOH)=+28.90.

EXAMPLE 2A

[0092]

2-Methoxy-1-(triisopropylsilyloxy)benzene

[0093] To a solution, under nitrogen, of guiacol (1.0 g, 8.06 mmol) inDMF (20 mL) at ambient temperature add imidazole (1.15 g, 16.9 mmol) andtriisopropylsilyl chloride (2.6 mL, 12.08 mmol). Allow reaction for 23.5h and then pour into saturated NaHCO₃ solution (35 mL). Extract theaqueous mixture with hexane (3×50 mL), combine the extracts, wash with1M HCl (50 mL), H₂O (50 mL) and dry over MgSO₄. Filter through Na₂SO₄and concentrate under vacuum. Distill the product with a Kugelrohrapparatus under high vacuum and collect 2.14 g of colorless oil.

[0094] Anal. Calc. for C₁₆H₂₈O₂Si: C, 68.50; H, 10.08. Found: C, 68.45;H, 9.92. CIMS (CH₄): m/z=281 (81%), 237 (100%). IR (KBr): 2945, 2868,1504, 1458, 1282, 1267, 920, 745 cm⁻¹. ¹H NMR (CDCl₃): δ 6.90-6.75 (4H), 3.79 (3 H, s), 1.32-1.19 (1 H, m), 1.09 (6 H, d, J=7.1 Hz). ¹³C NMR(CDCl₃): δ (ppm) 150.9, 145.5, 121.3, 120.7, 120.5, 112.2, 55.4, 17.9,12.9.

EXAMPLE 2B

[0095]

4-(2-Methoxy-3-triisopropylsilanyloxy-benzoyl)-piperidine-1-carboxylicacid tert-butyl ester

[0096] Cool in a dry ice/acetone bath under nitrogen, a solution of2-methoxy-1-(triisopropylsilyloxy)benzene, Example 2A (0.560 g, 2.00mmol) in dry THF (5.0 mL) and add 2.5M n-butyllithium in hexane (3.2 mL,8.0 mmol) over 5 minutes. After 10 minutes more allow the reaction towarm to 0° C., then after 4 hours, to 20° C. for 2h, and then to refluxfor 0.5 hour. Cool the reaction to −78° C. and treat with neat4-(N-methoxy-N-methylcarboxamido)-1-piperidinecarboxylic acid tert-butylester (prepared as described in U.S. Pat. No. 5,134,139) (0.653 g, 2.40mmol). Allow the reaction to warm to 20° C. After 16 h, treat thereaction with saturated NH₄Cl/H₂O (2 mL) and water (10 mL) and extractwith CH₂Cl₂ (2×20 mL). Dry the combined extracts (Na₂SO₄), concentrateunder vacuum, and chromatograph over silica gel eluting initially with10:90 ethyl acetate/hexane, and then 20:80 ethyl acetate/hexane,isolating the component with an R_(f)˜0.35 in the latter system. Removethe unreacted guaiacol contaminant from a CH₂Cl₂ solution of thechromatographed material with a 1M NaOH/H₂O wash to obtain the titlecompound as an oil (0.543 g, 55%).

[0097] Anal. Calc. for C₂₇H₄₅NO₅Si: C, 65.95; H, 9.22; N, 2.85. Found:C, 66.01; H, 9.15; N, 3.02. CIMS (CH₄): m/z=492 (8%), 436 (100%), 392(25%). IR (KBr): 2945, 2868, 1697, 1471, 1423, 1280, 1173cm⁻¹. ¹H NMR(CDCl₃): δ (ppm) 6.94(3H,m), 4.06 (2H, bd),3.84 (3 H, s), 3.23 (1 H, tt,J=11.2, 4.0Hz), 2.85 (2 H, bt, J=12.2 Hz), 1.84(2 H, dd, J=13.2, 3.0Hz), 1.59(2 H, m), 1.45(9 H, s), 1.30(3 H, m), 1.12(18 H, d, J=7.1 Hz).¹³C NMR (CDCl₃): δ 206.1, 154.7, 149.4, 148.8, 134.7, 124.1, 123.2,120.8, 79.4, 61.6, 47.8, 43.3 (broad), 28.4, 27.8, 17.8, 12.8.

EXAMPLE 2C

[0098]

{1-[2-(4-Fluoro-phenyl)-ethyl]-piperidin-4-yl}-(2-methoxy-3-triisopropylsilanyloxy-phenyl)-methanone

[0099] Stir and cool in an ice bath under nitrogen,4-(2-methoxy-3-triisopropylsilanyloxy-benzoyl)-piperidine-1-carboxylicacid tert-butyl ester, Example 2B (5.71 g, 11.6 mmol) and addtrifluoroacetic acid (30 mL). Remove the cold bath after 10 minutes.After 2 h, concentrate the reaction under vacuum at 40-45° C. and thenpour into saturated aqueous NaHCO₃. Extract the basic layer with CH₂Cl₂(2×200 mL), dry (Na₂SO₄), and concentrate under vacuum to an oil, whicheventually solidifies to afford4-(2-methoxy-3-triisopropylsilanyloxy-benzoyl)-piperidine.

[0100] Dissolve the crude amine from above in dry acetonitrile (60 mL),treat with diisopropylethylamine (4.9 mL, 28.2 mmol) and add2-(4-fluorophenyl)ethyl-1-mesylate, (synthesis is described in U.S. Pat.No. 4,221,817) (3.07 g, 14.1 mmol). Heat the reaction at reflux undernitrogen for 24 hours, cool, treat with saturated aqueous NaHCO₃ (50mL), and extract with CH₂Cl₂ (150 mL). The combined extracts were dried(MgSO₄) and concentrated under vacuum to an oil. Purify the product bycolumn chromatography over silica gel, eluting with 30:70 ethylacetate/hexane to give 4.72 g (80%) of oil (Rf˜0.3 streaking).

[0101] Anal. Calc. for C₃₀H₄₄FNO₃Si: C, 70.13; H, 8.63; N, 2.73. Found:C, 70.03; H, 8.52; N, 2.88. CIMS (CH₄): m/z=514 (70%), 404 (100%). IR(neat): 2945, 2868, 1690, 1510, 1470, 1296, 1222,956 cm⁻¹. ¹H NMR(CDCl₃): δ (ppm) 7.17-7.11(2 H, m), 6.97-6.91(5 H), 3.84 (3 H, s), 3.08(1 H, m), 2.97 (2 H, m), 2.76 (2 H, dd), 2.55 (2 H, dd), 2.10 (2 H, dt),1.91 (2 H, bd), 1.80-1.68 (2 H), 1.37-1.24 (3 H, m), 1.10 (18 H). ¹³CNMR (CDCl₃): δ 206.6, 162.9, 159.7, 149.4, 148.7, 136.1, 135.0, 130.0,129.9, 124.1, 123.0, 120.8, 115.2, 114.9, 61.5, 60.7, 53.2, 47.9, 32.9,28.1, 17.9, 12.8. ¹⁹F NMR (CDCl₃): δ −118.061 (m).

EXAMPLE 2D

[0102]

{1-[2-(4-Fluoro-phenyl)-ethyl]-piperidin-4-yl}-(3-hydroxy-2-methoxy-phenyl)-methanone

[0103] Add to a solution of{1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-(2-methoxy-3-triisopropylsilanyloxy-phenyl)-methanone,Example 2C (1.80 g, 3.50 mmol) in dry THF (5 mL) at ca. 20° C. undernitrogen, 1.0 M tetrabutylammonium fluoride in THF (4.55 mL, 4.55 mmol).After stirring 5 h, dilute the reaction with brine (100 mL) and extractwith CH₂Cl₂ (3×75 mL). Dry the extracts (Na₂SO₄) and concentrate undervacuum. Purify the crude product by column chromatography over silicagel eluting initially with 50:50 ethyl acetate/hexane then 5:95methanol/ethyl acetate giving the product as an oil (R_(f)˜0.2 in ethylacetate), which solidifies after standing. Triturate the solid withhexanes and recrystallize from hot ether (˜30 mL) by cooling andconcentrating under a nitrogen stream to ˜10 mL. Collect the resultingslightly orange crystals to obtain 1.04 g (83 %) of the title compound,mp 100-101° C.

[0104] Anal. Calc. for C₂₁H₂₄FNO₃: C, 70.57; H, 6.77; N, 3.92. Found: C,70.24; H, 6.72; N, 4.03. CIMS (CH4): m/z=358 (100%), 338 (28%), 248(96%). IR (KBr): 3437, 2957, 1684, 1510, 1221 cm⁻¹. ¹H NMR (CDCl₃): δ(ppm) 7.14 (2 H, m), 7.06 (1 H, s), 7.04 (1 H, d, J=2.1 Hz), 6.95 (3 H,m), 3.81(3 H, s), 3.09(1 H, m), 3.01(2 H, m), 2.77 (2 H, dd, J=9.3, 11.0Hz), 2.57 (2 H, m), 2.14 (2 H, dt, J=2.3, 11.4 Hz), 1.82 (4 H, m). ¹³CNMR (CDCl₃): δ 205.5, 163.0, 159.7, 149.3, 145.2, 135.9, 135.9, 132.8,130.0, 129.9, 124.8, 120.1, 118.7, 115.2, 114.9, 62.8, 60.6, 53.2, 47.3,32.7, 28.1. ¹⁹FNMR (CDCl₃): δ −117.913(m).

EXAMPLE 2E

[0105]

Sulfuric acidmono-(±)-[3-({1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-hydroxy-methyl)-2-methoxy-phenyl]ester

[0106] To a 7 mL glass screw cap tube add acetonitrile (200 μL),pyridine (200 μL), sulfur trioxide pyridine complex (20 mg, 130 μm) and{1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl}-(3-hydroxy-2-methoxy-phenyl)-methanone,Example 2D (5.2 g, 15.2 μm). Place on a heating block and heat at 100°C. for 2h. Cool and concentrate under vacuum (Savant concentrator), anddissolve residue in absolute ethanol (0.5mL). Add NaBH₄ (30 mg) and thenquench with acetic acid (100 μL). Dilute the reaction mixture 1/40 with20:80 acetonitrile/buffer (0.17M acetic acid with 0.5M ammonium acetate)and analyze by LC/MS/MS (Zorbax RX , C8, 5μm, 2.1×150 mm, buffer: 0.17Macetic acid and 0.05M ammonium acetate/acetonitrile; 75/25, Flow: 0.15mL/min) t_(R)=6.83 min. CIDMS m/z=440 (M+H⁾⁺. ¹H NMR (300 MHz, DMSO-d₆)δ (ppm) =7.40 (d, 1H), 7.35 (t, 2H), 7.12 (t, 2H),7.00 (d, 1H), 6.95 (d,2H), 4.95 (s, 1H), 4.63 (t, 1H), 3.79 (s, 3H), 3.50-2.40 (series ofbroad peaks, 9H), 1.90-1.40 (series of broad peaks, 5H). ¹³C NMR (75MHz, DMSO-d₆) δ (ppm)=162.25, 159.95, 147.75, 145.59, 137.02, 130.05,122.20, 121.5, 119.95, 115.05, 115.00, 69.03, 60.09, 57.00, 52.00,33.33, 29.02, 26.02, 25.00, 24.05. ¹⁹F NMR (376 MHz, DMSO-d₆) δ(ppm)=−117.00.

[0107] The compounds of the present invention antagonize the effects ofserotonin at the human 5-HT_(2A)-type serotonin receptor as shown bystandard binding data. Conversely, the compounds of the presentinvention do not show any significant affinity at the following humanreceptors: dopamine-D₂; serotonin-5HT_(2C); alpha adrenergic-α_(1A) asshown by standard binding methods.

EXAMPLE 3 Receptor Binding Assays

[0108] Cells stably expressing the human homologs of the receptors(dopamine D_(2L), serotonin 5HT_(2A) and 5HT_(2C), α_(1A) adrenergic;cloned and expressed at Hoechst Marion Roussel; Grandy et al., 1989;Monsma et al., 1993; Schwinn et al., 1995) were grown; cell membraneswere prepared, and kept frozen until used (Kongsamut et al., 1996). Therelevance of these binding sites has been extensively discussed in theliterature (see for example: Carlsson & Carlsson, 1990; Creese et al.,1976; Gorman & Vargas, 1995; Meltzer et al., 1989). All bindingparameters were optimized at Hoechst Marion Roussel; ligand K_(d)s weredetermined using both saturation analysis (Scatchard) as well as kineticanalysis (association and dissociation rates). Each batch of membranewas validated by checking the ligand K_(d), and rank order of potency ofselected standard compounds. Assays for the serotonin 5HT_(2A) anddopamine D_(2L) receptors were conducted at 37° C. in a Tris buffercontaining salts (50 mM Tris Buffer, pH 7.7; 120 mM NaCl; 5 mM KCl; 2 mMCaCl₂; 1 mM MgCl₂), while the serotonin 5-HT_(2C) and α1A adrenergicreceptor assays used a different buffer without salts (50 mM Tris, 4 mMCaCl₂ and 1% ascorbate, pH 7.4). Various binding parameters (ligand,ligand concentration, incubation times, ligand K_(d)s, displacing agentto define specific binding and tissue/cell line used) are summarized inthe Table below (Closse et al., 1983; Hall et al., 1990; Leysen et al.,1977).

[0109] Membranes were rapidly thawed and diluted to an appropriateconcentration (between 20-150 μg protein/assay point depending onreceptor expression level) in Tris buffer and homogenized. Assay plateswere incubated at 37° C. in an incubator for the times indicated. Theassay was stopped by rapid filtration and washing (15 mL ice-cold 0.05MTris buffer, pH 7.7) through Packard GF/B Unifilter plates (presoaked in0.5% polyethyleneimine) using a Tomtec 96-well Cell Harvestor.Microscint scintillation cocktail (40 μl) were added and the filterplates were counted in a Packard Top Count scintillation counter. Datawere analyzed to determine Ki's for compounds of interest (Prusoff &Cheng, 19). Table: Receptor Binding Parameters. All Scatchard analyseswith the ligands below showed a single site; displacement of the ligandswas assumed to be single site displacements. ligand [conc.] incubationtime ligand Kd non-specific receptor ligand (nM) (min) (nM) bindingcell/tissue human [³H]N-methylspiperone 1 60 0.09  10 μM CHO D_(2L)(−)eticlopride human [³H]N-methylspiperone 1.5 40 0.92  30 μM BHK5-HT_(2A) methysergide human [³H]mesulergine 2 40 1.9 100 nM CHO5-HT_(2C) mianserin human [³H]prazosin 1 40 0.19  10 μM CHO α_(1A)phentolamine

[0110] References:

[0111] 1. Carlsson, M., Carlsson, A. Interactions between glutamatergicand monoaminergic systems within the basal ganglia—implications forschizophrenia and Parkinson's disease. Trends Neural Sci 13: 272-276,1990.

[0112] 2. Closse, A. M. [³H]Mesulergine, a selective ligand for 5HT₂receptors. Life Sci. 32: 2485-2495, 1983.

[0113] 3. Creese, I., Burt, D. R., Snyder S. H. Dopamine receptorbinding predicts clinical and pharmacological potencies ofantischizophrenic drugs. Science 192: 481-483, 1976.

[0114] 4. Grandy, D. K., Marchionni, M. A., Makam, H., Stofko, R. E.,Alfano, M., Frothingham, L., Fischer, J. B., Burke-Howie, K. J., Bunzow,J. R., Server, A. C. and Civelli, O. Cloning of the cDNA and gene for ahuman D₂ dopamine receptor. Proc. Nat. Acad. Sci. U.S.A. 86: 9762-9766,1989.

[0115] 5. Hall, H., Wedel, I., Halldin, C., Kopp, J & Farde, L.Comparison of the in vitro Receptor Binding Properties ofN-[³H]Methylspiperone and [³H]raclopride to Rat and Human BrainMembranes. J. Neurochem. 55: 2048-2057, 1990.

[0116] 6. Kongsamut, S., Roehr, J. E., Cai, J., Hartman, H. B.,Weissensee, P., Kerman, L. L., Tang, L. & Sandrasagra, A. Iloperidonebinding to human and rat dopamine and serotonin receptors. Eur JPharmacol 317: 417423, 1996.

[0117] 7. Leysen, J. E., Gommeren, W. & Laduron, P. M. Spiperone: Aligand of choice for neuroleptic receptors. Biochem. Pharmacol. 27:307-328 (1977).

[0118] 8. Meltzer, H. Y. Clinical studies on the mechanism of action ofclozapine: the dopamine-serotonin hypothesis of schizophrenia.Psychopharmacol 99: S18-S27, 1989.

[0119] 9. Monsma, F. J., Jr, Shen, Y., Ward, R. P., Hamblin, M. W. &Sibley, D. R. Cloning and expression of a novel serotonin receptor withhigh affinity for tricyclic psychotropic drugs. Molec. Pharmacol. 43:320-327, 1993.

[0120] 10. Schmidt, C., Sorensen S. M., Kehne, J. H., Carr, A. A. &Palfreyman, M. G. The role of 5HT_(2A) receptors in antipsychoticactivity. Life Sci. 56: 2209-2222, 1995.

[0121] 11. Schwinn, D. A., Johnston, G. I., Page, S. O., Mosley, M. J.,Wilson, K. H., Worman, N. P., Campbell, S., Fidock, M. D., Furness, L.M., Parry-Smith, D. J., et al. Cloning and pharmacologicalcharacterization of human alpha-1 adrenergic receptors: sequencecorrections and direct comparison with other species homologues. J.Pharmacol. Exp. Ther. 272:134-142, 1995.

[0122] 12. Vargas, H. M. & Gorman, A. J. Vascular alpha-1 adrenergicreceptor subtypes in the regulation of arterial pressure. Life Sci. 57:2291-2308, 1995.

[0123] All of the forgoing references are incorporated herein byreference.

[0124] In vitro inhibition of [³H]-Ligand binding to human ⁵-HT2A, D₂,⁵HT_(2C) and α_(1A) receptors Compound 5HT_(2A) (K_(i) μM) D₂ (K_(i) μM)5HT_(2C) (K_(i) μM) α_(1A) (K_(i) μM) Example 1H 0.16 >1.0 >1.0 >1.0

[0125] The compounds of this invention are capable of crossing theblood-brain barrier (BBB) as shown by their ability to penetrate acrossa membrane of a monolayer of bovine brain microvessel endothelial cells,an in vitro model for BBB permeability.

EXAMPLE 4 Bovine Brain Endothelial Cells (BBMEC) Transport Studies

[0126] The procedure was performed according to: Kenneth L. Audus etal., Brain Microvessel Endothelial Cell Culture System (Chapter 13) pp239-258. In Models for Assessing Drug Absorption and Metabolism, RonaldT. Borchardt et al. eds., Plenum Press, New York 1996, incorporatedherein by reference. The test compounds are run at two concentrations(5.4 μM and 16 μM) and the apparent permeability coefficient is reportedas P_(app) in cm/sec and values reported as mean±standard deviation.

In vitro BBMEC Permeability

[0127] In vitro BBMEC permeability P_(app)(×10⁵ cm/sec) P_(app)(×10⁵cm/sec) Compound at 5.4 μM at 16 μM Mannitol (standard) 2.76 ± 0.23 2.76± 0.23 Example 1H 4.14 ± 0.69 3.44 ± 0.86

What is claimed is:
 1. A method of isolating a compound of formula I orits enantiomers from an appropriate sample comprising the steps of:

a) collecting the sample from a patient wherein the patient has beenadministered a therapeutically sufficient amount of(+)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol;b) optionally preparing the sample for isolation of the compound ofFormula I or its enantiomers; and c) isolating the compound of Formula Ior at least one enantiomer from the sample.
 2. A method according toclaim 1 wherein the sample is plasma.
 3. A method according to claim 1wherein the sample is urine.
 4. A method according to claim 1 whereinisolating is by chromatography.